Compositor: Buffer iterators

Currently we mostly iterate buffer areas using x/y loops or through
utility methods extending from base classes.

To simplify code in simple operations this commit adds wrappers for
specifying buffer areas and their iterators for raw buffers with any
element stride:
- BufferRange: Specifies a range of contiguous buffer elements from a
 given element index.
- BufferRangeIterator: Iterates elements in a BufferRange.
- BufferArea: Specifies a rectangle area of elements in a 2D buffer.
- BufferAreaIterator: Iterates elements in a BufferArea.
- BuffersIterator: Simultaneously iterates an area of elements in an
 output buffer and any number of input buffers.
- BuffersIteratorBuilder: Helper for building BuffersIterator adding
 buffers one by one.
For iterating areas coordinates it adds `XRange` and `YRange` methods
that return `IndexRange`.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D11882

1 files changed, 23 insertions, 0 deletions

diff --git a/source/blender/compositor/COM_defines.h b/source/blender/compositor/COM_defines.h
index 9f8e6f10215..0e97bafbb0b 100644
--- a/source/blender/compositor/COM_defines.h
+++ b/source/blender/compositor/COM_defines.h
@@ -18,6 +18,9 @@
 
 #pragma once
 
+#include "BLI_index_range.hh"
+#include "BLI_rect.h"
+
 namespace blender::compositor {
 
 enum class eExecutionModel {
@@ -109,4 +112,24 @@ constexpr float COM_PREVIEW_SIZE = 140.f;
 constexpr float COM_RULE_OF_THIRDS_DIVIDER = 100.0f;
 constexpr float COM_BLUR_BOKEH_PIXELS = 512;
 
+constexpr IndexRange XRange(const rcti &area)
+{
+  return IndexRange(area.xmin, area.xmax - area.xmin);
+}
+
+constexpr IndexRange YRange(const rcti &area)
+{
+  return IndexRange(area.ymin, area.ymax - area.ymin);
+}
+
+constexpr IndexRange XRange(const rcti *area)
+{
+  return XRange(*area);
+}
+
+constexpr IndexRange YRange(const rcti *area)
+{
+  return YRange(*area);
+}
+
 }  // namespace blender::compositor